An imaging device such as a digital camera for imaging a subject and recording image data of the subject on a recording medium has been spread rapidly. Such an imaging device is composed of an imaging optical system such as a zoom lens, a charge-coupled device (CCD) image sensor (solid state imaging device) for converting an optical image into an electric signal, a signal processing circuit for processing an imaging signal outputted from the CCD image sensor and converting the imaging signal to image data, and the like.
The imaging device has been improved in various points so as to satisfy demand for achieving high function of the imaging optical system and demand for downsizing of the imaging device, which are conflicted to each other. As a result of such an improvement, there is known a digital camera incorporating a lens device having a so-called path bending optical system in which optical path is bent by a prism (see Japanese Patent Laid-Open Publication No. 2005-351930).
In the lens device having the path bending optical system, light from an object-side lens facing a subject is bent at a right angle by the prism, and the bent light is focused on an imaging surface of the solid state imaging device by lens groups. The lens groups are disposed such that the optical axes thereof extend in the vertical direction when a camera body is held in a normal position. The lens groups move along the direction of the optical axis (longitudinal direction of the camera body) in accordance with zooming operation. Accordingly, the imaging device adopting the lens device having the path bending optical system is much thinner than conventional imaging devices.
Further, in a digital camera described in Japanese Patent Laid-Open Publication No. 2005-351930, a lens device includes a first section and a second section. The first section houses lens groups. The second section houses two motors aligned in the vertical direction. One of two motors severs for driving the lens groups for zooming, and the other of them serves for driving the lens groups for focusing. The thickness of the second section is made thinner than that of the first section, and a display part such as liquid crystal display (LCD) is arranged to be partially superposed on a rear surface of the second section. Thereby, the total thickness of the digital camera is decreased.
Recently, the demand for further high magnification of the digital camera has been increasing. It has been required to adopt a zoom optical system for driving plural lens groups, in which the number of the movable lens groups is increased. However, the digital camera as described in Japanese Patent Laid-Open Publication No. 2005-351930 has a problem in which one motor is necessary for driving one movable lens group, and therefore when the number of the movable lens groups is increased, the number of the necessary motors is also increased, and thus causing upsizing of the digital camera. Moreover, when a cam ring is used to drive plural movable lens groups, there arises a problem in which the thickness of the digital camera is also increased.